Temperature compensated pneumatic time delay devices



y 1962 F. A. KOMATAR ETAL 3,037,101

TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Filed Feb. 9, 19592 Sheets-Sheet 1 fin nnn F G 2 Q INVENTORS FREDERICK A. KOMATAR BY FRANKARTHUR PEARSON ATTORNEY May 29, 1962 F. A. KOMATAR ETAL 3,037,101

TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Filed Feb. 9, 19592 Sheets-Sheet 2 T\\[\ P I FIG 4 I sa a 'i'g 20' o ///////////7/FREDERICK A. KOMATAR FRANK ARTHUR PEARSON IN VENTORS.

ATTDRNEY United States Patent Ofifice 3,037,101 Patented May 29, 1962TEMPERATURE COMPENSATED PNEUMATIC TIME DELAY DEVICES Frederick A.Komatar, East Moline, and Frank Arthur Pearson, Moline, 111., assignors,by mesne assignments, to The Gamewell Company, Newton, Mass, :1corporation of Delaware Filed Feb. 9, 1959, Ser. No. 792,167 24 Claims.(Cl. 20083) The invention relates to devices which hold a manually orelectrically actuated switch in actuated position for a fixed time.

More specifically, the invention relates to electrically or mechanicallyoperated pneumatic timers which include means for compensating foratmospheric temperature change to maintain timing accuracy Withintolerance limits at all times.

The invention will be described as applied to manually operable shorttiming range pneumatic timers adapted to control one or more electricswitches of the snap acting type. Other improvements to timing devicescontemplated in the present invention include ease of manufacture,economy of parts, and low cost of assembly.

Timing by displacing a given volume of air which is then replacedthrough a metering device by atmospheric pressure is well known. What isbelieved to be new is to meter the return air through an orifice whichchanges its flow capacity with atmospheric temperature change to therebycompensate for temperature-viscosity changes in the air. In the past, asthe temperature of the air increased, the timing interval decreased. Asan analogy, the air may be compared to a liquid which becomes more fluidas its temperature is increased. Being more fluid, the air is morerapidly aspirated through the orifice thus reducing the timing interval.

Employment of a captive atmosphere in the timing chamber does noteliminate the problem because the timer is normally at or above ambienttemperature because of the heating action of the operating solenoid orother control apparatus. This raises the temperature of the captiveatmosphere, thereby decreasing the timing interval.

The invention compensates for change of air temperature by changing thecross sectional area of the orifice. This is accomplished by the use ofmaterials having dissimilar temperature coefficients of expansion, onematerial forming the needle valve and another material forming the valvesleeve or housing.

Another feature of the invention permits adjustment of the needle in thesleeve without rotation. Thus the needle cannot scar the sleeve and thesleeve cannot groove the needle. Flats on the non-metering portions ofthe needle and the sleeve prevent rotation and allow only longitudinalmovement. The needle and the sleeve have substantially identical tapersand thus do not injure each other.

Another feature of the invention provides that the needle valve cannotbe forced into the valve orifice by continuously turning the adjustmentknob. The knob merely backs off.

Another feature of the invention is the employment of approximately 90percent captive air thus permitting the elimination of the filternormally required. Make-up air is admitted on the underside of thedevice around the stem thereby greatly reducing the amount of grit ordirt entering the chamber. An opening to the atmosphere is required sothat pressure will not build up within the chamber as the temperature ofthe timer body is increased.

Another feature of the invention is the design of the needle valveadjustment means which permits partial withdrawal of the needle valvefor eiiecting instantaneous time-out during an emergency or duringset-up when the operator does not want to wait for the device to timeout.

An additional advantage of the design is that during the power stroke'air is forced through both the check valve and the orifice thusproviding a cleansing action for the orifice.

Other advantages will be evident as the invention is described inconjunction with the following figures of which:

FIGURE 1 is an exterior view of the timer shown in pers ective.

FIGURE 2 is a cross sectional view of the timer, having one form ofmetering orifice, shown in actuated position.

FIGURE 3 is an isometric view of the diaphragm retainer and diaphragm.

FEGURE 4 is a cross sectional view of an alternate form of the meteringorifice.

FIGURE 5 is a plan view of the switch lever.

Description An exterior view of the timer is shown in FIGURE 1. Theenclosure consists of a mounting plate 1, a base 2, and a cap 3. Each ofthese three pieces is die cast and is ready for assembly essentially asit comes from the die. Switch 4 may be any one of a variety ofcommercially available snap acting switches and is affixed to the base 2with mounting screws 5. The switch 4 includes terminals 6, 7 which arenormally open and are closed by the action of switch lever 9 when button8 is depressed thereby energizing an external load circuit, not shown.After the preset delay period has transpired, switch lever 9 permitsswitch 4 to open the circuit between terminals 6 and 7 and the externalload is deenergized. A reverse acting switch having normally closedcontacts may be used in place of switch 4 which has normally opencontacts. Then the load would be energized continuously and deenergizedduring timing. A double throw switch may be used to obtain either of theswitching arrange,- ments described above.

A cross sectional View of the timer is shown in FIGURE 2. The section istaken through the centerline of the device and illustrates thesimplicity of design.

Mounting plate 1 carries a raised flange portion 11 having a centerbore12 which acts as a guide for button 8. Mounting plate 1 also has afulcruma13 for switch lever 9. Four spacer posts 14 are cast integrallywith mounting plate 1 and support the base 2 and the cap 3 of the timer.Rivet-like extensions, not shown, on posts 14 are expanded afterassembly to rivet the cap, base, and mounting plate into an integralunit.

Timer base 2 forms one portion of the air chamber and has an integrallycast cavity 15 and air passage 16. Base 2 has a centrally locatedopening 17 for the stem 18 of the diaphragm retainer 20. Base 2 has acounterbore 21 adapted to seat one end of the switch actuator spring 22.Spring 22 is spaced from stem 18 and thus cannot cause wear or frictionaffecting timer accuracy. The spacing between stem 18 and opening 17 issufi'icient to allow entrance of air during depression of button 8 thuspermitting the partial vacuum formed in chamber 15 to be equalized withatmospheric pressure. Air compressed in chamber 23 moves through thecheck valve into chamber 15 during depression of button 8. A smallportion of the air compressed in chamber 23 moves through the meteringorifice and passage 15 into chamber 15 thus performing a slightcleansing action within the metering orifice.

Cap 3 forms and encloses the other portion of the air chamber 23 havinga frusto conical interior which -con forms closely to the frusto conicalexterior of the top of diaphragm retainer 20. Diaphragm 27 divides thechamber into two portions and is clamped around its periphery by base 2and cap 3 by the compression action of the rivet extensions of posts 14.The diaphragm is set in a counter-bore 19 which prevents excessivecompression of the diaphragm during the riveting operation.

Diaphragm 27 serves also as support for diaphragm retainer 20 which isretained thereon by ring 33 which forms also the check valve seat 25.Rivet-like projections 34 formed as part of diaphragm retainer 20 serveto hold the ring 33 to the retainer 29. The rivet-like projections 34are superior to other fastening devices such as screws or rivets becausethey do not require a hole through retainer 20. They provide a positiveseal and prevent air leakage from one portion of the chamber to theother.

There are openings 26 in the diaphragm 27 which are eflectively sealedby check valve assembly 24. A check valve cap 35 is supported by thediaphragm 27. The check valve washer 36 is drawn against the diaphragm27 and check valve cap 35 by the rivet action of projection 37 whichforms a part of check valve cap 35 and extends through the diaphragm andwasher 36. The resiliency of the diaphragm 27 combined with the springaction of the check valve spring 38 maintains closure of the checkvalve. Check valve spring 38 is a simple leaf spring and exertsapproximately one ounce of force tending to hold the diaphragm 27against the check valve seat 25. Since the check valve seat is a ringhaving a conical cross section with a very small area impressed on thediaphragm, the small spring force creates a high seating pressure aroundthe apex of the ring. Air is ex hausted from the chamber 23 to cavity 15through openlugs 26 in the diaphragm 27 and thence through ports 30 inthe retainer 20.

The diaphragm and retainer assembly is shown in isometric view in FIGURE3. Referring to FIGURES 2 and 3, diagram 27 is in the preferred form acircular sheet of fiber glass reinforced silicone rubber. Diaphragm '27is compressed between retainer 2-0 (not shown) and ring 33 by the actionof rivet-like projections 34. The check valve cap 35 (not shown) ispositioned below the diaphragm 27 in a recess in retainer 20. A washer36 and a projection 37 on check valve cap .35 retain cap 35 on diaphragm27. The check valve seat 25 is formed as an integral part of ring 33.There are a number of openings 26 in diaphragm 27 under the ring 33 anda number of ports 30 in the retainer 20 which permit passage of air fromabove to below the diaphragm 27 when the retainer stem 18 is forcedupward.

Referring again to FIGURE 2, depression of button 8 forces stem 18 anddiaphragm retainer 20 away from cavity 15 toward chamber 23 forcing theair in chamber 23 to displace the check valve portion of diaphragm 27away from check valve seat 25 and pass through aperture 26 in diaphragm27 around check valve spring 38, through ports 30 in diaphragm retainer20 and into cavity 15. A small portion of the air compressed in chamber23 moves out through the needle valve orifice 29 into valve housing 32,through passage 16 into chamber 15 at a high velocity. This cleans outany dust in the metering orifice 29.

During the timing portion of the cycle spring 22 forces button 8 andstem 18 of diaphragm retainer 20 forward creating a partial vacuum incavity 23 and a pressure differential across the diaphragm. The pressuretends to equalize through passage 16, around the needle valve 31, andthrough the tapered orifice 29. Needle valve hous' ing 32 is die cast aspart of cap 3 and has an interior of circular cross section and has aflat surface 43 along one side. The body of needle valve 31 is ofcircular cross section with a flat on one side. The two flats bear oneach other and prevent the needle valve 31 from rotating whenbinding-type stop nut 44 is rotated for timing adjustment. This preventsthe orifice surfaces from galling. As another precaution, the frustoconical surface 40 of needle valve 31 has burnished into the metal poresof its surface a graphite type lubricant. All surplus lubricant isremoved from the surface to prevent stoppage of the air passage anderratic timing.

Needle valve 31 has preferably an elongated form with a slight taper atone end and a screw thread at the other end. Its means of attachment andadjustment is located at the extreme outer end to make its effectivelength as great as possible. in this way it expands and contractssubstantially longitudinally with temperature change. Its high ratio oflength to width is used to advantage in the invention. Prior art valveswere attached near the needle end or near the center, rather than at theoutboard end.

None of the timers on the market today, to our knowledge, offertemperature compensation.

The needle valve 31 is in the preferred form of the invention turnedfrom bronze having a temperature coefficient of expansion ofapproximately 0.00000986 inch per inch per degree Fahrenheit. The valvehousing 32 which forms a part of cap 3 is cast of brass having atemperature coefficient of expansion of approximately 0.00000957 inchper inch per degree Fahrenheit. The principle of the combination is thatas the ambient temperature rises and the air becomes more fluid theneedle 31 elongates and expands a greater amount than the housing 32 anddecreases the orifice area. Various combinations of metallic ornon-metallic materials may be selected to accomplish this change inorifice area. To eliminate casting the cap 3 of solid brass, a sleeve ofbrass may be inserted in an aluminum or zinc cap 3 as shown in FIGURE 4.

A screw thread is applied to the outer end of needle valve 31 to permitits axial adjustment. Needle valve bushing 46 is pressed into acounterbore 47 in valve housing 32 and acts as a guide for needle valve31 and a stop for spring 48 which is seated around a raised flange onbushing 46. The other end of spring 48 is seated around a flange onneedle valve 31. The intervening portion of the needle valve 31 is ofsmaller cross section to prevent wear. Spring 48 supplies sufficientcompression to maintain needle valve 31 at any time setting.

It will be noted that continuous rotation of stop nut 44 in the counterclockwise direction will permit spring 48 to move the needle valve 31further into the orifice 29 lengthening the timing interval. If stop nut44 is turned until it is loose, spring 48 will limit the compression ofthe needle 31 in orifice 29. Since spring 48 exerts only a limitedforce, needle 31 cannot score or gal-l orifice 29- Continued rotation ofstop nut 44 in the clockwise direction compresses spring 48 and movesneedle valve 31 further out of orifice 29 and shortens the timinginterval.

A snap acting switch 4 is afiixed to a flange 513 which is a part of diecast base 2. Self tapping screws 5 are used. A rectangular piece ofinsulating fabric (not shown) may be applied between the switch 4 andflange 50 to provide additional insulation between terminals 6, 7 andbase 2 and cap 3.

Snap switch 4 is actuated by the action of switch lever 9 againstactuator 51. The inside end of switch lever 9 resides in a groove 52turned in button 8. A fulcrum 13 formed as part of mounting plate 1serves as a pivot for switch lever 9 shown in plan view in FIGURE 5. Tworaised portions 53 adjacent to fulcrum 13 coact with two notches 54 inswitch lever 9 to give it lateral stability. The inner end of switchlever 9 is formed with two fingers 55 which coact with the groove 52 inbutton 8 to stabilize the lever and transmit force to it. Switch lever 9is maintained in a vibration free state by the spring within switch 4behind actuator 51 and by the spring 22. Rollpin 56 serves to retainstem 13 in engagement with button 8. A reduced section on stem 18engages a bore in button 8 for proper alignment. Button 8, stem 18,diaphragm retainer 2'0 and diaphragm 27 act as a unitary structure.

The structure is retained by the guide 12 in mounting plate 1 and bydiaphragm 27. Diaphragm 27 holds one end of the structure in alignmentand guide 12 and button 8 hold the other end in alignment. The structureis thus restrained against all movement except axial translation.

Another form of the temperature compensating mechanism is shown inFIGURE 4. As stated above, the cost of die casting cap 3 may be reducedby casting it of zinc or aluminum rather than brass and by inserting abrass sleeve in housing 32 to produce the same temperature compensatingeffect.

As shown in FIGURE 4-, a sleeve 41 is inserted in the valve housing 32which is cast as part of cap 3. Valve housing 32 has an interior ofhexagonal cross section. The sleeve 41 has an exterior of hexagonalcross section to prevent rotation in housing 32 and has a keyway 42 outalong one side. The body of needle valve 31 is of circular cross sectionwith a radial bore fitted with a pin 49 projecting from one side forsliding in keyway 42. The pin 43 in the needle valve 31 fits into thekeyway 42 on one side of valve sleeve 41 and prevents the needle valve31 from rotating When knob 57 is rotated for timing adjustment. Thisprevents the orifice surfaces from galling.

The passage of air around the exterior of valve sleeve 41 is preventedby the quad ring 53. Quad ring 58 is compressed between the end of valvesleeve 41 and the end of valve housing 32. The sleeve 41 is retained inhousing 32 by a bushing 59 pressed into the outer end of housing 32.

The sleeve 41 is in this embodiment bored from brass hex stock having atemperature coefiicient of expansion of approximately 0.00000957 inchper inch er degree Fahrenheit. The needle valve 31 is turned from bronzehaving a temperature coefiicient of expansion of approximately0.00000986. As the ambient temperature rises and the air becomes morevolatile the needle 31 expands a greater amount than the housing 32 anddecreases the orifice area. Various combinations of metallic ornonmetallic materials may be employed to accomplish this change inorifice area. The remainder of the device is substantially identicalwith that described above.

One feature of the invention which contributes to increased timingaccuracy for a pneumatic timer is the design of the air chamber 23 andthe diaphragm retainer 20. As shown in FIGURE 2 with the button 8 fullydepressed, retainer 20* and diaphragm 27 and associated parts completelyfill the chamber 23 and expel all the air therefrom. Then, when thetimed interval commences when the actuating force is removed from button8 only the very small amount of air trapped in the passage above thechamber 23 expands into chamber 23. A good vacuum is thus obtained, theamount of vacuum depending on the force of spring 22'. Little travel ofthe retainer stem 18 is lost as the remaining air expands. Thisincreases the linearity of the timing curve.

It is understood that a solenoid and plunger may be installed in placeof pushbutton 8 to make the timer operable electrically and remotely. Itis also understood that various sized models of the timer could be madeto extend the range of timings available.

We claim:

1. A temperature compensated pneumatic time delay device comprising, aswitch device adapted to be actuated after a fixed delay, asubstantially airtight timing chamber, means for expelling substantiallyall of the air from said chamber, resilient means for drawing air intosaid chamber, a self compensating temperature compensated orificedetermining the time required to replace the air, means to actuate theswitch device when the air is substantially replaced.

2. A temperature compensated pneumatic timer consisting of a timingchamber having a frusto conical interior, a flexible diaphragm closingsaid chamber, a mating frusto conical means for moving said diaphragm toexpel substantially all of the air from said chamber, a spring urgingsaid means away from said interior thereby reducing the pressure in saidchamber below atmospheric, and adjustable means for admitting atmosphereto said chamber having integral temperature compensation, said meanscomprising a frusto conical valve opening of one material and anelongated frustro conical needle valve of a different material having asomewhat greater temperature coefiicient of expansion.

3. A timer comprising a confined chamber having a frusto conicalinterior, means fitting into said chamber having a frusto conicalexterior for pressurizing said chamber, a flexible diaphragm separatingsaid means and said chamber, check valve means in said diaphragm forreleasing the air in said chamber to atmosphere, means tending to drawsaid first named means out of said chamber, self temperaturecompensating air metering means between atmosphere and said chamber,said means comprising an orifice of variable cross sectional area, saidorifice defined by a bore in a material having a given temperaturecoefiicient of expansion, and an elongated needle valve coextensivetherewith of a material having a greater temperature coeflicient ofexpansion, said elongated needle valve adjustable at the outboard endthereof, the area of said orifice decreased as the temperature of saidtimer increases, and increased as the temperature of said timerdecreases.

4. A timer comp-rising, a cap made of a material having a given thermalcoeificient of expansion, a tapered bore in said cap, a correspondinglytapered needle valve having an elongated body made of a material havinga somewhat greater thermal coefiicient of expansion supported at itsexterior end by said cap and extending into said tapered bore andslidably movable therein under manual and thermal adjustment, manualadjustment means comprising a screw thread on the exterior end of saidneedle valve and a friction nut and spring cooperative with said cap topermit and retain manual adjustment of said needle valve, thermaladjustment comprising the lengthening and shortening of said needlevalve with timer temperature increase and decrease, respectively, adiaphragm having one-way valve means therein, said diaphragm underexternal urging adapted to expel substantially all the air from saidcap, spring means effective after release of said external urgingadapted to said diaphragm means away from said cap to reduce the airpressure therein, an air passage from atmosphere into said cap includingsaid needle valve and said tapered bore to meter atmosphere into saidcap, and switch means actuated by said diaphragm means when the airpressure in said cap is substantially restored.

5. An interval timer consisting of a cap having an air chamber with afrusto conical interior, a diaphragm across the base of said frustoconical interior, a base having an air chamber with a cylindricalinterior, said cap and said base secured together and securing the rimof said diaphragm, a diaphragm retainer secured to and centered on saiddiaphragm and having a conical forepart and a cylindrical aft part and astem, means to urge said retainer and diaphragm forward into saidconical air chamber to compress the air therein, one-way valve means insaid diaphragm and retainer designed to permit the passage of aircompressed in said conical chamber into said cylindrical chamber, an airpassage between said chambers having a metering orifice therein,additional means to urge said retainer and diaphragm aftward to form apartial vacuum in said conical chamber, the air metered into saidconical chamber permitting said retainer and diaphragm to move aftwardat a rate governed by said metering orifice, the metering orificemanually preset to permit the conical chamber to fill in a fixed time,the fixed time maintained over a wide range of operating temperatures bythe temperature compensating effect of said metering orifice, saidmetering orifice ineluding a tapered bore in said cap and a long needlevalve having a correspondingly tapered end coextensive therewith, saidtemperature compensating efiect obtained from the temperature elongationof said needle, said needle being made of a material having asubstantially greater temperature coetficient of expansion than saidcap, the elongation of said needle being sufiicient to overcome both thetemperature expansion of said orifice and the change of fluidity of theair with temperature, and an electric switch controlled by the forwardand aftward movement of said stem.

6. In a timer of the class described, a unitary structure consisting ofa mounting plate, a base, and a cap, said base and cap affixed to saidmounting plate, said base and said cap having coaxial air chambers, aflexible diaphragm separating said chambers, said diaphragm compressedaround its periphery between said cap and said base, a retainer atfixedto said diaphragm, said retainer held from all but axial. movementthereby, a stem on said retainer adapted to pass through a bore in saidmounting plate, means to urge said stem and said retainer toward saidcap to compress the air in said chamber in said cap, check valve meansincluding said diaphragm to release said compressed air to the chamberin said base, resilient means to ur e said retainer toward said base tocreate a partial vacuum in said chamber in said cap, an air passagebetween said chambers, a metering orifice in said air passage, saidmetering orifice comprising a slightly tapered bore in said cap and aneedle having a correspondingly tapered end, said needle having a finescrew thread on its opposite end, a bushing in said cap adapted toslidingly support said opposite end of said needle, a compression springmounted on said bushing and adapted to urge the tapered portion of saidneedle into said tapered bore, nut means threaded on said fine screwthread exterior to said air passage adapted to regulate the excursion ofsaid needle into said tapered bore, said needle having a flat on oneportion of its length, said air passage in said cap having acorresponding flat to prevent rotation of said needle, said needle madeof a material having a greater coefficient of thermal expansion than thematerial of said cap, the air moving through said orifice in onedirection during compression and in the opposite direction duringtiming, the metering orifice kept free of dust by said air movement, andswitch means actuated by said retainer.

7. In a new article of manufacture, a pneumatic time delay device havinga body consisting of a die cast mounting plate, a base, and a cap, saidbase and said cap having centrally located apertures, a pushbuttonadapted to be mounted in said plate and axially movable therein, a stemafiixed to the inside end of said pushbutton mounted in said base andaxially movable therein, a helical compression spring around said stemand adapted to urge said pushbutton away from said base, a cylindricalchamber in said base, an air tight frusto conical chamber in said cap, aflexible diaphragm compressedly retained between said cap and said base,a corresponding frusto conical diaphragm retainer formed on one end ofsaid stem, said diaphragm retainer and stem maintained against sidewaysmotion by said diaphragm, a one-way valve in said diaphragm comprised ofa ring rigidly fixed to said diaphragm retainer and having a conicalshaped valve seat therein, a check valve cap fixed to said diaphragm, acheck valve spring between said retainer and said valve cap for biasingsaid diaphragm against said check valve seat, ports in said diaphragmretainer and in said diaphragm beyond said check valve seat, said checkvalve adapted to release air from said chamber when the pressure thereinis somewhat greater than atmospheric, an adjustable metering orificebetween the two said chambers consisting of an elongated passage in saidcap fitted with a sleeve having a given temperature coetficient ofexpansion and having a central bore and a tapered orifice therein, aneedle valve having a greater temperature coefficient of expansion andhaving a correspondingly tapered. end, a radial bore in the centerportion of said Cir needle, a pin fitted into said bore and projectingtherefrom, a longitudinal slot in said sleeve adapted to take theprojection of said pin, said needle having a threaded portion extendingbeyond said sleeve, an elastic nut threaded on said thread and abuttingsaid sleeve, a compression spring between said needle and an interiorridge on said sleeve to maintain said needle in said orifice as far assaid nut permits, a return passage from said orifice to said cavity, atwo position snap acting switch aflixed to said base, an actuator a partof said switch, a switch lever adapted to pivot on a portion of saidmounting plate, one end of said switch lever adapted to coact With saidbutton, the other end of said switch lever adapted to bear on saidactuator, said switch urged to one position when said button isdepressed and to the other position a predetermined delay interval aftersaid button is released, said delay remaining substantially constantwithin wide ambient temperature limits.

8. A pneumatic time delay device including a housing, first and secondchambers in said housing, a diaphragm separating said chambers, an airpassage between said chambers, a conical bore forming one portion ofsaid passage, a cylindrical bore having a flat across one chord forminga second portion of said passage, a needle valve made of a materialhaving a greater thermal coetlicient of expansion than said chamber andadapted for axial movement in said cylindrical and conical bores andhaving a flat along one side for cooperation with said flat in saidcylindrical bore, a compression spring mounted around said needle andadapted to urge said needle toward said conical bore, a screw thread onthe outboard end of said needle and a nut beyond said cylindrical borefor manual longitudinal adjustment of said needle, the thermalproperties of said needle applying longitudinal adjustment of saidneedle with temperature change, said needle kept from turning by saidflats to keep the conical surfaces from galling during adjustment, andmeans to create a partial vacuum in said first chamber, and meansbecoming effective when suflicient air has passed through said passageto reduce the vacuum and to actuate a switch.

9. A pneumatic time delay device including first and second airchambers, said diaphragm compressed between said chambers at itsperiphery, a gastight, flexible diaphra gm between said chambers, adiaphragm retainer compressed against the lower surface of saiddiaphragm, a ring having a circular central recess compressed againstthe upper surface of said diaphragm, rivet-like projections on saidretainer extending through holes in said diaphragm and said ring forriveting said ring to said retainer, a check valve comprising additionalholes in said diaphragm located within the confines of said recess, anda washer and spring urging said diaphragm against said ring, saidretainer having holes substantially opposite said additional holes insaid diaphragm, means to move the retainer and diaphragm assembly tocreate a pressure in said first chamber, said check valve operated bythe resulting air pressure to reduce it to substantially atmospheric, aspring adapted to move said retainer and diaphragm assembly to create apartial vacuum in said first chamber, an integral temperaturecompensating metering orifice between said first and second chambers tometer air into said first chamber, and an electric switch actuated bysaid retainer when sufiicient air has been admitted to said chamber.

10. A temperature compensated time delay device in which one diaphragmserves as a timing diaphragm and a check valve diaphragm, including airusto conical chamher and a cylindrical chamber, a flexible diaphragmof fiberglass reinforced silicone rubber separating said chambers, acylindrical diaphragm retainer mounted on one side of said diaphragm, afrusto conical ring mounted on the other side of said diaphragm andaflixed to said retainer by leak-proof rivet-like projections on saidretainer, said ring having an annular sealing flange and an annularrecess adjacent to said flange, one or more ports in said diaphragmopposite said recess, a spring loaded valve disc urging said diaphragmagainst said sealing flange, one or more apertures in said retaineropposite said ports, the check valve portion of said diaphragm thusarranged to permit release of air compressed in said conical chamber,means to urge said diaphragm from said cylindrical chamber into saidconical chamber to rapidly displace substantially all of the air fromsaid conical chamber, means to urge said diaphragm slowly toward saidcylindrical chamber, a passage containing a self temperaturecompensating metering orifice between said two chambers, and an electricswitch actuated from said retainer after a time delay.

11. In a pneumatic time delay device having two chambers separated by anairtight diaphragm, a one-way air passage through the diaphragm betweenthe two chambers, a restricted air passage between the two chambers, anon-self-damaging metering orifice comprising the restriction, themetering orifice consisting of a bore and a needle valve having aportion slidable therein, said needle valve having also an elongatedthreaded portion, a thumb nut adapted for threading onto said threadedportion, a sleeve a part of said device having an opening adapted toguide said needle valve longitudinally, a helical spring compressedbetween said sleeve and a flange on said needle valve urging said needlevalve into said orifice, the needle valve limited in its travel by theadjustment of said thumb nut, continued untightening rotation of saidthumb nut causing said thumb nut to unseat rather than said needle valveto scar said orifice, continued tightening rotation of said thumb nutcausing said needle valve to withdraw from said orifice.

12. A temperature compensated pneumatic time delay device comprising, aswitch actuated at the beginning of a delay period and at the end of thedelay period, a substantially airtight timing chamber, externallyoperated means for expelling substantially all of the air from saidchamber, spring means for drawing air into said chamber, a selftemperature compensating elongated needle valve and orifice determiningthe rate of replacement of the air into said chamber, and lever meansadapted to actuate the switch device as the air is substantiallyreplaced.

13. A temperature compensated pneumatic timer consisting of a timingchamber having a frusto conical interior, a flexible diaphragm closingsaid chamber, a mating frusto conical means for moving said diaphragm toexpel substantially all of the air from said chamber, a spring urgingsaid means away from said interior thereby reducing the pressure in saidchamber below atmospheric, and adjustable means for admitting atmosphereto said chamber having an integral temperature compensating orifice,said orifice comprising a tapered bore into said chamber and anelongated tapered needle anchored a substantial distance axially awayfrom said tapered bore and adapted to expand and contract substantiallyaxially into and out of said tapered bore, the axial movement of saidneedle resulting from the thermal expansion and contraction thereof,said thermal expansion and contraction being suflicient to compensatefor the expansion and contraction of said bore and the increase anddecrease in viscosity of the air with temperature changes materiallylarge.

14. The safety feature in a pneumatic time delay device having anorifice, means for adjustably partially closing said orifice, said meansincluding an elongated needle valve having adjusting means on itsexterior end external to said device, spring means urging said needlevalve into said orifice, said spring means cooperative with saidadjusting means for maintaining said needle valve in its last adjustedposition, said timing device immediately timing out upon manualwithdrawal of said adjusting means.

15. A pneumatic timer having an orifice, means for adjustably partiallyclosing said orifice, said means including an elongated needle valvehaving a fine adjusting screw thread on its exterior end at leastpartially external to said timer, spring means urging said needle valveinto said orifice, said spring means cooperative with said adjustingmeans for maintaining said needle valve in its last adjusted position,and thumb nut means having a fine thread cooperative with said fineadjusting screw thread on the exterior end of said needle valve forobtaining fine adjustment thereof.

116. A pneumatic time delay device having a choice of two timingintervals, one being an adjustable, timed interval and the other being avery short untimed interval; said device comprising a gastight chamberhaving diaphragm means externally operated to substantially reduce thevolume of said chamber, check valve means designed to Vent the gascompressed in said chamber, spring means adapted to urge said diaphragmmeans to increase the volume of said chamber, a metering orificeconnected to said chamber through which entering gas is metered,adjustable means for metering said gas to determine the time required tosubstantially fill said chamber, said adjustable means capable of rapidwithdrawal to permit filling said chamber in a very short time to reducethe waiting time on a mechanism controlled thereby, and electric switchmeans operable by said diaphragm means.

17. A pneumatic time delay device having a self-protecting orifice,means for adjustably partially closing said orifice, said meansincluding a needle valve having adjusting means external to said device,a compression spring urging said needle valve into said orifice, saidspring cooperative with said adjusting means for maintaining said needlevalve in its last adjusted position, said adjusting means rotatable inone direction to withdraw said needle from said orifice to therebyshorten the timing interval, said adjusting means rotatable in theopposite direction to extend said needle into said orifice to therebylengthen the timing interval, said adjusting means adapted to back ofiwhen said needle meets said orifice, and said compression springeffective to limit the force of said needle against said orifice.

18. In a timer of the class described, a unitary strac ture consistingof a mounting plate, a base, and a cap, said base and cap affixed tosaid mounting plate, said base and said cap having coaxial chambers, aflexible diaphragm separating said chambers, a counterbore in said capcoaxial with the chamber in said cap, said counterbore of lesser depththan the thickness of said diaphragm, said diaphragm positioned in saidcounterbore and compressed around its periphery between said cap andsaid base, a retainer 'aflixed to said diaphragm, sad retainer held fromall but axial movement thereby, a stem on said retainer adapted to passthrough a bore in said mounting plate, means to urge said stem and saidretainer toward said cap to compress the gas in said chamber in saidcap, check valve means including said diaphragm to release saidcompressed gas to the chamber in said base, resilient means to urge saidretainer toward said base to create a partial vacuum in said chamber insaid cap, a gas passage between said chambers, a metering orifice insaid passage, and an electric switch operated by the axial movement ofsaid stem.

19. In an article of manufacture, a pneumtic time delay device having abody consisting of a mounting plate, a base, and a cap, said plate andsaid base having centrally located apertures, a pushbutton adapted to bemounted in said plate and axially movable therein, a stem alfixe-d tosaid pushbutton, a compression spring around said stern and adapted tourge said push-button away from said base, a chamber in said base, anair tight chamber in said cap, a flexible diaphragm compressedlyretained between said cap and said base, a diaphragm retainer afiixed toone end of said stem, said diaphragm retainer and stem maintainedagainst sideways motion by said diaphragm, a one way valve in saiddiaphragm comprised of a ring rigidly fixed to said diaphragm retainerand having a valve seat therein a check valve cap fixed to saiddiaphragm, a check valve spring between said retainer and said valve capfor biasing said diaphragm against said check valve seat, ports in saiddiaphragm retainer and in said diaphragm beyond said check valve seat,said check valve adapted to release air from said chamber when thepressure therein is somewhat greater than atmospheric, an adjustablemetering orifice between the two said chambers consisting of anelongated passage in said cap having a given temperature coefficient ofexpansion and including a central bore and a tapered orifice, a needlevalve having a greater temperature coefficient of expansion and having acorrespondingly tapered end, said needle adapted for only longitudinalmovement in said passage, said needle having a threaded portionpartially extending beyond said passage, a nut threaded on said threadand abutting said passage, a compression spring between said needle andan interior ridge in said passage to maintain said needle in saidorifice as far as said nut permits, a return passage from said orificeto said cavity, a two position snap acting switch afiixed to said base,an actuator a part of said switch, a switch lever adapted to pivot on aportion of said mounting plate, one end of said switch lever adapted tocoact with said button, the other end of said switch lever adapted tobear on said actuator, said switch urged to one position when saidbutton is depressed and to the other position a predetermined delayinterval after said button is released, said delay remainingsubstantially constant within wide ambient temperature limits.

20. A pneumatic time delay device consisting of a mounting plate, abase, and a cap, said plate and said base having coaxial borestherethrough, a timer actuator adapted to be mounted through said borein said plate and axially movable therein, a spring adapted to urge saidactuator away from said base, a chamber in said base coaxial with saidbore, a coaxial chamber in said cap, a flexible diaphragm compressedyretained between said cap and said base, a diaphragm retainer in part ofsaid actuator, said retainer and actuator retained from sideways motionby said diaphragm, a check valve in said diaphragm consisting of a ringaffixed to said retainer and having a valve seat therein, a check valvecap fixed to said diaphragm, a check valve spring between said retainerand said valve cap for biasing said diaphragm against said check valveseat, holes in said retainer and in said diaphragm beneath said ring,said check valve adapted to release pressure from said chamber when thepressure therein is somewhat greater than without, an adjustable orificeconsisting of a passage in said cap having a given temperaturecoefficient of expansion, a needle valve having a greater temperaturecoefficient of expansion, said needle adapted for non-rotationallongitudinal movement in said passage, said needle having a threadedportion extending outside said passage, a correspondingly threadedadjustment means exterior to said passage, a spring between said passageand said needle for urging said needle into said orifice, a switch apart of said device, a switch actuator a part of said switch, a leveradapted to pivot on a portion of said device and coast with saidactuator and said switch actuator, said switch urged to one positionwhen said timer actuator is actuated and to the other position a presetdelay interval after said timer actuator is released, said delayremaining substantially constant within wide ambient temperature limits.

21. A pneumatic time delay device consisting of a mounting plate, abase, and a cap, a rod adapted to protrude through said base and moveaxially therein, a spring adjacent said rod and adapted to urge said rodaway from said base, a cylindrical chamber in said base, a frustoconical chamber in said cap, a flexible diaphragm compressedly retainedbetween said cap and said base, a corresponding frusto conical diaphragmretainer formed on one end of said rod, said diaphragm retainer and rodmaintained against sideways motion by said diaphragm, a one way valve insaid diaphragm comprised of a ring rigidly fixed to said diaphragmretainer and having a valve seat therein, a check valve cap fixed tosaid diaphragm, a check valve spring between said retainer and saidvalve cap for biasing said diaphragm against said check valve seat,ports in said diaphragm retainer and in said diaphragm beyond said checkvalve seat, said check valve adapted to release air from said chamberwhen the pressure therein is somewhat greater than without, anadjustable metering orifice between the two said chambers consisting ofan elongated passage in said cap having a given temperature coefi'icientof expansion and having a central bore and an orifice therein, a needlevalve having a greater temperature coefficient of expansion, means toprevent rotation of said needle in said passage, said needle having athreaded portion extending beyond said chamber, means for longitudinaladjustment or" said needle, a spring adapted to urge said needle intosaid orifice as far as said adjustment means permits, a return passagefrom said orifice to said chamber in said base, a switch aflixed to saidbase, an actuator a part of said switch, a switch lever having one endadapted to coact with said rod and the other end adapted to bear on saidswitch actuator, said lever urged to one position when said rod isdepressed and to the other position a predetermined delay interval aftersaid rod is released, said relay remaining substantially constant withinwide ambient temperature limits,

22. A pneumatic time delay device consisting of a mounting plate, abase, and a cap, said base and said cap having centrally locatedapertures, a pushbutton axially movable therein, a spring affixed to theend thereof and adapted to urge said pushbutton away from said base, acylindrical chamber in said base, an air tight frusto conical chamber insaid cap, a flexible diaphragm retained between said cap and said base,a corresponding frusto conical diaphragm retainer attached to one end ofsaid stem, a one way valve in said diaphragm, a check valve cap fixed tosaid diaphragm, a check valve spring between said retainer and saidvalve cap for biasing said diaphragm against said check valve seat,ports in said diaphragm retainer and in said diaphragm beyond said checkvalve seat, said check valve adapted to release air from said chamherwhen the positive pressure therein is somewhat greater than atmospheric,an adjustable metering orifice between the two said chambers consistingof an elongated passage in said cap fitted with a sleeve having a giventempera ture coefficient of expansion and having a central bore and atapered orifice therein, a needle valve having a greater temperaturecoefiicient of expansion and having a correspondingly tapered end, saidneedle having a threaded portion extending beyond said sleeve,adjustment means threaded into said thread and abutting said sleeve, aspring between said needle and said sleeve to maintain said needle insaid orifice as far as said adjustment means permits, a return passagefrom said orifice to said cavity in said base, a snap acting switchaffixed to said base, an actuator a part of said switch, a switch leverone end of which is adapted to coact with said button, the other end ofwhich is adapted to bear on said actuator, said switch urged to oneposition when said button is depressed and to the other position apredetermined delay interval after said button is released, said delayremaining substantially constant within wide ambient temperature limits.

23. A temperature compensated pneumatic time delay device comprising, anelectric switch, an airtight timing chamber having a flexible wall,means to both actuate said switch and expel air from said chamber, aspring tending to move said flexible wall back to its initial position,a temperature modified orifice which corrects for changes in airviscosity with temperature change permitting air to gradually flow backinto said timing chamber, means to actuate the switch when the flexiblewall of said timing chamber reaches its initial position.

24. A pneumatic time delay device that can readily be put out of actionhaving, in combination, a chamber below atmospheric pressure, an orificeadmitting air to 13 said chamber, an elongated needle extending intosaid orifice and partly restricting it, a spring holding said needle insaid position in said orifice, externally accessible means to draw saidneedle out of said orifice against said spring to allow the chamber tofill With air without delay.

References Cited in the file of this patent UNITED STATES PATENTS 14Ponstingl et al. Jan. 16, 1951 Lindahl Mar. 10, 1953 Schaefer July 14,1953 Schaefer Dec. 15, 1953 Opsahl Dec. 4, 1956 Nadrowski et a1 Oct. 8,1957 Bachi Dec. 30, 1958 Yarrick Apr. 14, 1959 Humim Apr. 14, 1959FOREIGN PATENTS Germany June 30, 1957

